The invention concerns a stent for the splinting and/or for the holding open of a hollow organ, with a tubular and self-expandable netting made from filaments, which, in a collapsed state, extends in an axial direction and in an extended state is shortened in the axial direction.
A stent of this kind has become known in the arm through EP 0 177 330 B1.
Stents of the known kind are, for example utilized for the treatment of vessel illnesses. Stents allow a vessel lumen to be permanently held open through their transluminal implantation. With the assistance of interventional radiology it is thereby possible to complement invasive surgery or, in an advantageous case, to render same unnecessary. The transluminal utilization of stents for the splinting or for the permanent extending of stenoses is particularly advantageous in patients with high surgical risk factors.
In addition to metallic memory protheses, which are made from nitinol wire, double helix spirals are known in the art for splinting and for keeping open a narrowing in a vessel which open a narrowed lumen in that they, by means of a known insertion instrument, are introduced into the appropriate location of the vessel and expanded in place. The double helix spiral is held in place via its own expanding forces against the wall of the vessel.
Also known is a "Palmaz-stent" which comprises a thin-wall tube made from rust-free steel and exhibiting longitudinal slits. The tube-shaped stent is mounted, for purposes of insertion, onto a dilating balloon and through insufflation of the balloon, is expanded and released in place. A net-like structure is formed by the expansion of the tube shaped stent.
The stent known from EP 0 177 330 B1 comprises a steel wire which is shaped in a zig-zag form. When pressed together it is possible to insert the stent through a catheter placed in the vessel whereby after expulsion, the stent automatically expands under its own forces. The internal forces of the known stent can be varied through the choice of the strength of the rounded wire, the degree of pre-bending, and the number of zig-zag bends. A disadvantage of this system, is possible breakage due to material fatigue of the round wire in the vicinity of the particularly highly stressed "Z-portions".
It is the underlying purpose of the invention to further improve a self-expanding stent of the above mentioned kind in that, by means of improved expansion behaviour, as protective a seating as possible of the filaments on the inner walls of the hollow organ is guaranteed and a removal of the inserted stent is made, in a simpler fashion, possible.